Suppose that you examine a vial of 100 flies that are all offspring from a single genetic cross. Suppose also that you see that all the females present are red-eyed and all the males present are white-eyed. The allele for red eye colour (Xw+) is dominant over the allele for white eye colour (Xw). Which of the following describes the genotypes of the parents?
a. Xw+Xw; XwY
b. XwXw; Xw+Y
c. Xw+Xw+; XwY
d. Xw+Xw; Xw+Y
Ans: b. XwXw; Xw+Y
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Two alleles of the same gene ________.
A. are always different B. can be the same or can be different C. are always the same D. originate from the same parent
Some plasmids can replicate in several distinct species of bacteria. Frequently these plasmids have transposons carrying several different antibiotic resistance genes. In a hospital that has an outbreak of several species of bacteria each carrying resistance to three drugs (streptomycin, gentamicin, and penicillin), what is the best way to determine whether or not this resistance is due to a single shared plasmid with all three resistance genes?
A) Demonstrate that all the resistant bacteria have a plasmid. B) Isolate plasmids from all resistant bacterial species and demonstrate that drug-sensitive cells from these same species become resistant to all three drugs when this plasmid is transformed. Confirm that the same plasmids are present in all species by sequencing the plasmid DNA. C) Sequence the genomes of the resistant species and demonstrate mutations in the same homologous genes. D) Isolate plasmids from one resistant species and transform a drug-sensitive strain of the other bacterial species to see if resistance occurs in the transformants.
Seventy to 90 percent of the genetic material in a gamete made in your body could be inherited from your mother. How could this be?
a. The above statement is incorrect. Fifty percent of the genetic material in your gametes comes from your father. b. You receive maternal genes through the placenta and through breast milk. c. The X chromosome is substantially larger than the Y chromosome. d. Your maternal genes kill off your paternal genes at a greater rate than your paternal genes kill off your maternal genes. e. You receive many mitochondria, which have their own genome, from your mother, but not from your father.
Prokaryotic cells lack:
A) DNA. B) ribosomes. C) internal compartmentalization. D) proteins.